Amino Group to a Diazonium Ion The Sandmeyer Reaction

Converting an Amino Group to a Diazonium Ion The Sandmeyer Reaction 

The diazonium ion results from the reaction of an aniline with nitrous acid (HNO ), prepared by treating sodium nitrite with sulfuric acid. This step is called diazotization. 

In 1884, the German chemist Traugott Sandmeyer found that diazonium ions react with nucleophiles supplied in the form of a Cu(I) salt. These nucleophiles replace the diazonium group and release nitrogen gas. These reactions are known collectively as the Sandmeyer reaction. 

For example, an aromatic diazonium ion can be treated with Cu Cl to yield chlorobenzene or with CujBr to give bromobenzene. 

Aryl diazonium compounds react with hot aqueous acid to give phenols. This is the best way to attach an —OH group to an aromatic ring. 

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